How should Glargine (insulin glargine) be managed in the perioperative setting?

Glargine Management in the Perioperative Setting

Continue basal insulin glargine at 60-80% of the usual dose in the perioperative period, maintaining it throughout NPO status to prevent both hyperglycemia and ketoacidosis while minimizing hypoglycemia risk. 1, 2

Preoperative Management

Timing and Dosing

• Administer 60-80% of the patient's usual glargine dose the evening before surgery 1, 3
• The optimal dose appears to be approximately 75% of the normal dose, which achieves target blood glucose (100-180 mg/dL) in 78% of patients while minimizing hypoglycemia 3
• Schedule diabetic patients as early as possible in the morning to avoid prolonged fasting 4

Critical Distinction by Diabetes Type

• Type 1 diabetes patients require continuous basal insulin even when NPO to prevent diabetic ketoacidosis 1, 2
• Type 2 diabetes patients also benefit from continued basal coverage but have lower risk of ketoacidosis 1

Intraoperative Management

Transition to IV Insulin

• When insulin is required intraoperatively, use ultra-rapid short-acting analogues administered continuously by IV infusion (IVES) 4
• Always administer IV insulin with IV glucose (equivalent of 4 g/h) and electrolytes to prevent hypokalaemia 4
• If the patient uses a personal insulin pump, remove it and immediately initiate IVES insulin at the start of the intervention 4

Glycemic Targets

• Maintain blood glucose between 5-10 mmol/L (90-180 mg/dL) 4
• Avoid strict normoglycemia (80-120 mg/dL), which increases severe hypoglycemia and possibly mortality 4
• Hyperglycemia >10 mmol/L (180 mg/dL) increases morbidity, particularly infections, and mortality 4

Monitoring Requirements

• Measure blood glucose every 1-2 hours during surgery 4
• Check potassium every 4 hours in patients receiving insulin 4
• Use arterial or venous blood rather than capillary blood, as glucometers overestimate levels, especially during vasoconstriction 4

Postoperative Management

Resuming Subcutaneous Insulin

• Restart glargine at the doses used during hospitalization when the patient can eat 4
• Administer ultra-rapid analogue insulin at the first meal, adapting to carbohydrate intake 4
• Continue basal insulin (glargine) even if the patient remains NPO temporarily 1, 5

Transition from IV to Subcutaneous

• When converting from IV insulin infusion to subcutaneous glargine: give half the total 24-hour IV insulin dose as once-daily glargine in the evening 4
• Ensure blood glucose levels are stable for at least 24 hours before transitioning 1

Monitoring and Adjustment

• Check blood glucose every 4-6 hours while NPO 1, 2
• If blood glucose falls below 100 mg/dL, decrease glargine dose by 10-20% 1
• For blood glucose <70 mg/dL (3.8 mmol/L), administer glucose immediately even without symptoms 4
• For blood glucose 70-100 mg/dL with symptoms, administer glucose 4

Discharge Planning Based on HbA1c

Well-Controlled Diabetes (HbA1c <8%)

• Resume previous treatment at hospitalization doses 4
• Schedule follow-up with treating physician within 1-2 weeks 4

Moderately Controlled (HbA1c 8-9%)

• Resume previous treatment 4
• Request consultation with diabetologist for therapy intensification 4

Poorly Controlled (HbA1c >9% or blood glucose >11 mmol/L)

• Continue basal-bolus scheme (glargine plus rapid-acting insulin) 4
• Arrange urgent diabetology consultation 4

Critical Pitfalls to Avoid

Never Discontinue Basal Insulin Completely

• Complete cessation in Type 1 diabetes can precipitate diabetic ketoacidosis within hours 2
• Even in Type 2 diabetes, stopping basal insulin leads to severe hyperglycemia and metabolic decompensation 1, 2

Avoid Mixing or Diluting Glargine

• Do not mix glargine with other insulins or solutions 6
• Glargine coprecipitates with short-acting insulins when co-administered in the same syringe 7

Monitor for Stress Hyperglycemia

• In patients with HbA1c <6.5% who develop hyperglycemia, this represents stress hyperglycemia 4
• Taper insulin progressively as blood glucose normalizes 4
• 60% of these patients will develop diabetes within one year, requiring follow-up fasting glucose at one month and annually 4

Recognize Hypoglycemia Risk Factors

• Patients with insulin resistance may require higher percentages of basal insulin (closer to 80%) 1
• Elderly patients and those with renal/hepatic dysfunction require more conservative dosing 6
• Point-of-care glucometer reading of 70 mg/dL should be considered hypoglycemia requiring immediate action 4